Polymer HPLC materials

The silica gel-based column packings are the active materials of choice for polymer HPLC employing both exclusion and interaction retention mechanisms. These are either bare or bonded with various groups. C-18 alkyls and -CH2-CH2-CH2-NH2 groups are most popular for reversed-phase and normal-phase procedures of polymer HPLC employing the nonpolar and polar interactions, respectively. 

Silica-base stationary phases have also been employed for enantiomeric separations in CEC [6,72-81]. In the initial work on chiral CEC, commercially available HPLC materials were utilized, including cyclodextrins [6,74,81] and protein-type selectors [73,75,80] such as human serum albumin [75] and ai-acid glycoprotein [73]. Fig. 4.9, for example, depicts the structure of a cyclodextrin-base stationary phase used in CEC and the separation of mephobarbital enantiomers by capillary LC and CEC in a capillary column packed with such a phase. The column operated in the CEC mode affords higher separation efficiency than in the capillary LC mode. Other enantiomeric selectors are also use in CEC, including the silica-linked or silica-coated macrocyclic antibiotics vancomycin [82,83] and teicoplanin [84], cyclodextrin-base polymer coated silicas [72,78], and weak anion-exchage type chiral phases [85]. Relatively high separation efficiency and excellent resolution for a variety of compounds have also been achieved using columns packed with naproxen-derived and Whelk-0 chiral stationary phases linked to 3 pm silica particles [79]. Fig. 4.10 shows the... 

Additionally liquid-liquid (partition) HPLC can be performed with packings which are polymer-coated materials such as those illustrated in Table 10.5. 

INSTRUMENTATION AND MATERIALS FOR POLYMER HPLC 11,6,1 APPARATUS FOR POLYMER HPLC... 

Straight tubings from stainless steel with polished inner walls are the common column material. Their diameter ranges from less than one nun (capillary columns) to several cm (preparative columns). The standard columns for analytical polymer HPLC have diameter of four to ten nun and length of (100 to 300) nun. Dimensions of columns for analytical SEC are (7.5-10 x 250-300) nun. Columns for the fast SEC are short and wide, with the diameters as large as 50 nun. 

Proteins are isolated and characterized with different chromatographic techniques. Depending on the protein, ion-exchange (lEX), size-exclusion (SEC), affinity (IMAC), hydrophobic interaction (HIC), and reversed-phase chromatography (RPLC) may be applied. Traditionally, separation materials with low mechanical stability and limited resolution were used. In recent years, HPLC materials were developed that offered the separation power required by the protein chemist. Now, pellicular ion-exchange resins as well as organic polymer monoliths exhibit high resolution at relatively short retention times, while... 

Svec Erantisek, and Regnier Ered E. Organic polymer support materials. In HPLC of biological molecules, Gooding K., Regnier E.E. (eds.), pp. 17-48. New York Marcel Dekker, 2002. 

Before polyacrylamides are sold, the amount of residual acrylamide is determined. In one method, the monomer is extracted from the polymer and the acrylamide content is determined by hplc (153). A second method is based on analysis by cationic exchange chromatography (154). For dry products the particle si2e distribution can be quickly determined by use of a shaker and a series of test sieves. Batches with small particles can present a dust ha2ard. The percentage of insoluble material is determined in both dry and emulsion products. 

The application areas for LC-MS, as will be illustrated later, are diverse, encompassing both qualitative and quantitative determinations of both high-and low-molecular-weight materials, including synthetic polymers, biopolymers, environmental pollutants, pharmaceutical compounds (drugs and their metabolites) and natural products. In essence, it is used for any compounds which are found in complex matrices for which HPLC is the separation method of choice and where the mass spectrometer provides the necessary selectivity and sensitivity to provide quantitative information and/or it provides structural information that cannot be obtained by using other detectors. 

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